Polishing apparatus

Abstract

The polishing apparatus is capable of precisely controlling polishing pressure, correctly positioning a press plate and uniformly polishing a workpiece. In the polishing apparatus, a holding head comprises: first pressing means for introducing a pressurized fluid into a first fluid chamber and pressing a main head section downward; second pressing means for introducing a pressurized fluid into a second fluid chamber and pressing a press plate downward; and third pressing means for introducing a pressurized fluid into a third fluid chamber and pressing the workpiece downward. With this structure, the workpiece is held on the lower side of an elastic sheet member, and the lower face of the workpiece can be polished by a polishing plate.

1. A polishing apparatus,
 comprising: 
 a polishing plate having an upper face, on which a polishing cloth is adhered; 
 a holding head having a lower face, on which a workpiece is held so as to press the workpiece onto the polishing cloth; and 
 a driving mechanism for relatively moving said polishing plate with respect to said holding head so as to polish a lower face of the workpiece, 
 wherein said holding head comprises: 
 a head base; 
 a main head section being attached on the lower side of the head base with a first diaphragm and capable of moving toward said polishing plate, said main head section having a press ring, which is provided on the lower side thereof and capable of pressing the polishing cloth; 
 a press plate being provided in the main head section with a second diaphragm and capable of moving toward said polishing plate; 
 the press plate including a lower plate portion; 
 an elastic sheet member being attached to an outer radial surface of the lower plate portion of the press plate; 
 a first fluid chamber being formed between the head base and the main head section and closed by the first diaphragm; 
 a second fluid chamber being formed between the main head section and the press plate and closed by the second diaphragm; 
 a third fluid chamber being formed between the lower face of the press plate and the elastic sheet member; 
 first pressing means for introducing a pressurized fluid into the first fluid chamber and pressing the main head section downward; 
 second pressing means for introducing a pressurized fluid into the second fluid chamber and pressing the press plate downward; and 
 third pressing means for introducing a pressurized fluid into the third fluid chamber and pressing the workpiece downward, and 
 whereby the workpiece is held on the lower side of the elastic sheet member, and the lower face of the workpiece can be polished. 
 
     
     
       2. The polishing apparatus according to  claim 1 ,
 wherein the third pressing means discharges the fluid in the third fluid chamber so as to give a sucking function to the elastic sheet member so that the elastic sheet member is capable of sucking and holding the workpiece. 
 
     
     
       3. The polishing apparatus according to  claim 1 .
 wherein a backing pad is adhered on a lower face of the elastic sheet member, and 
 the workpiece is held on the lower side of the backing pad. 
 
     
     
       4. The polishing apparatus according to  claim 1 , wherein:
 the main head section has a cylindrical shape and is vertically divided into an upper cylindrical part and a lower cylindrical part by a cylindrical partition member, the upper cylindrical part, the lower cylindrical part and the partition member having a common outer radius that is the outermost radius of the main head section; 
 the first fluid chamber is constituted by the head base entering the upper cylindrical part and the first diaphragm closing a space between the head base and the upper cylindrical part, and 
 the second fluid chamber is constituted by the press ring attached to the lower cylindrical part, the press plate provided in the lower cylindrical part and the second diaphragm closing a space between the lower cylindrical part and the press plate. 
 
     
     
       5. The polishing apparatus according to  claim 1 ,
 wherein a rotary shaft is connected to the head base, 
 the head base is rotated by rotating the rotary shaft, 
 the main head section is rotated with the first diaphragm, and 
 the press plate is rotated with the second diaphragm. 
 
     
     
       6. The polishing apparatus according to  claim 1 ,
 wherein a rotary shaft is connected to the head base, 
 the head base and the main head section are engaged by a first transmitting member so as to allow the main head section to move upward and downward, 
 the main bead section and the press plate are engaged by a second transmitting member so as to allow the press plate to move upward and downward, 
 the head base is rotated by rotating the rotary shaft, 
 the main head section is rotated with the first transmitting member, and 
 the press plate is rotated with the second transmitting member. 
 
     
     
       7. The polishing apparatus according to  claim 6 ,
 wherein the first transmitting member and the second transmitting member are pins. 
 
     
     
       8. The polishing apparatus according to  claim 4 ,
 wherein a center shaft is vertically extended from a center of the press plate, and 
 the center shaft is capable of fitting with a shaft hale of the head base, so that the press plate can be correctly positioned and transverse vibrations of the press plate can be prevented. 
 
     
     
       9. The polishing apparatus according to  claim 8 ,
 wherein a fluid path communicating with the third fluid chamber is formed in the center shaft, and 
 a pressurized fluid is introduced into the third fluid chamber via the fluid path. 
 
     
     
       10. The polishing apparatus according to  claim 1 ,
 wherein the bead base and the main head section respectively have engaging parts, which engage each other when the head base is moved upward, and 
 the engaging parts are slope faces, which are capable of correctly positioning the main head section with respect to the head base. 
 
     
     
       11. The polishing apparatus according to  claim 1 ,
 wherein the main head section and the press plate respectively have engaging parts, which engage each other when the head base is moved upward, and 
 the engaging parts are slope faces, which are capable of correctly positioning the press plate with respect to the main head section. 
 
     
     
       12. The polishing apparatus according to  claim 1 ,
 wherein the press ring includes: 
 a guide ring enclosing the workpiece so as to prevent the workpiece from jumping out, the guide ring pressing a part of the polishing cloth, which is located on the outer side of the workpiece; and 
 a dress ring enclosing the guide ring and grinding the polishing cloth. 
 
     
     
       13. The polishing apparatus according to  claim 1 ,
 wherein a guide ring is provided along an outer edge of the lower face of the press plate, the guide ring encloses the workpiece so as to prevent the workpiece from jumping out, and the guide ring presses a part of the polishing cloth, which is located on the outer side of the workpiece; and 
 the press ring includes a dress ring enclosing the guide ring and grinding the polishing cloth. 
 
     
     
       14. A polishing apparatus,
 comprising: 
 a polishing plate having an upper face, on which a polishing cloth is adhered; 
 a holding head having a lower face, on which a workpiece is held so as to press the workpiece onto the polishing cloth; and 
 a driving mechanism for relatively moving said polishing plate with respect to said holding head so as to polish a lower face of the workpiece, 
 wherein said holding head comprises: 
 a head base; 
 a main head section being attached on the lower side of the head base with a first diaphragm and capable of moving toward said polishing plate, said main head section having a press ring, which is provided on the lower side thereof and capable of pressing the polishing cloth; 
 a press plate being provided in the main head section with a second diaphragm and capable of moving toward said polishing place; 
 an elastic sheet member being attached on a lower face of the press plate; 
 a first fluid chamber being formed between the head base and the main head section and closed by the first diaphragm; 
 a second fluid chamber being formed between the main head section and the press plate and closed by the second diaphragm; 
 a third fluid chamber being formed between the lower face of the press plate and the elastic sheet member; 
 first pressing means for introducing a pressurized fluid into the first fluid chamber and pressing the main head section downward; 
 second pressing means for introducing a pressurized fluid into the second fluid chamber and pressing the press plate downward; and 
 third pressing means for introducing a pressurized fluid into the third fluid chamber and pressing the workpiece downward, and 
 whereby the workpiece is held on the lower side of the elastic sheet member, and the lower face of the workpiece can be polished; 
 wherein: 
 a rotary shaft is connected to the head base, 
 the head base and the main head section are engaged by a first transmitting member so as to allow the main head section to move upward and downward, 
 the main head section and the press plate are engaged by a second transmitting member so as to allow the press plate to move upward and downward, 
 the head base is rotated by rotating the rotary shaft, 
 the main head section is rotated with the first transmitting member, and 
 the press plate is rotated with the second transmitting member. 
 
     
     
       15. A polishing apparatus,
 comprising: 
 a polishing plate having an upper face, on which a polishing cloth is adhered; 
 a holding head having a lower face, on which a workpiece is held so as to press the workpiece onto the polishing cloth; and 
 a driving mechanism for relatively moving said polishing plate with respect to said holding head so as to polish a lower face of the workpiece, 
 wherein said holding head comprises: 
 a head base; 
 a main head section being attached on the lower side of the head base with a first diaphragm and capable of moving toward said polishing plate, said main bead section having a press ring, which is provided on the lower side thereof and capable of pressing the polishing cloth; 
 a press plate being provided in the main head section with a second diaphragm and capable of moving toward said polishing plate; 
 an elastic sheet member being attached on a lower face of the press place; 
 a first fluid chamber being formed between the head base and the main head section and closed by the first diaphragm; 
 a second fluid chamber being formed between the main head section and the press plate and closed by the second diaphragm; 
 a third fluid chamber being formed between the lower face of the press plate and the elastic sheet member; 
 first pressing means for introducing a pressurized fluid into the first fluid chamber and pressing the main head section downward; 
 second pressing means for introducing a pressurized fluid into the second fluid chamber and pressing the press plate downward; and 
 third pressing means for introducing a pressurized fluid into the third fluid chamber and pressing the workpiece downward, and 
 whereby the workpiece is held on the lower side of the elastic sheet member, and the lower face of the workpiece can be polished; 
 wherein: 
 the head base and the main head section respectively have engaging parts, which engage each other when the bead base is moved upward and disengage each other when the head base is moved downward, and 
 the engaging parts are slope faces, which are capable of correctly positioning the main head section with respect to the head base. 
 
     
     
       16. A polishing apparatus,
 comprising: 
 a polishing plate having an upper face, on which a polishing cloth is adhered; 
 a holding head having a lower face, on which a workpiece is held so as to press the workpiece onto the polishing cloth; and 
 a driving mechanism for relatively moving said polishing plate with respect to said holding head so as to polish a lower face of the workpiece, 
 wherein said holding head comprises: 
 a head base; 
 a main head section being attached on the lower side of the head base with a first diaphragm and capable of moving toward said polishing plate, said main head section having a press dug, which is provided on the lower side thereof and capable of pressing the polishing cloth; 
 a press plate being provided in the main head section with a second diaphragm and capable of moving toward said polishing plate; 
 an elastic sheet member being attached on a lower face of the press plate; 
 a first fluid chamber being formed between the head base and the main head section and closed by the first diaphragm; 
 a second fluid chamber being formed between the main head section and the press plate and closed by the second diaphragm; 
 a third fluid chamber being formed between the lower face of the press plate and the elastic sheet member; 
 first pressing means for introducing a pressurized fluid into the first fluid chamber and pressing the main head section downward; 
 second pressing means for introducing a pressurized fluid into the second fluid chamber and pressing the press plate downward; and 
 third pressing means for introducing a pressurized fluid into the third fluid chamber and pressing the workpiece downward, and 
 whereby the workpiece is held on the lower side of the elastic sheet member, and the lower face of the workpiece can be polished; 
 wherein; 
 the main head section and the press plate respectively have engaging parts, which engage each other when the press plate is axially moved in a first direction relative to the main head section and which disengage each other when the press plate is axially moved in a second direction that opposes the first direction, and 
 the engaging parts are slope faces, which are capable of correctly positioning the press plate with respect to the main head section.